1. Field of the Invention
The present invention relates to a semiconductor memory device including a circuit which converts data on a data bus from its original data pattern.
2. Description of the Related Art
In data transfer of a conventional nonvolatile semiconductor memory device, data on a data bus is output from an I/O pad without changing its pattern. In the conventional method, even when a number of data bits change from ALL“0” to ALL“1”, or from ALL“1” to ALL“0”, the data is transmitted without changing the pattern, resulting in an increase in current consumption. A data inversion technique is known as a solution to this problem. The data inversion technique can reduce the number of times of transitions in inversion of a logic circuit.
For data transfer using the conventional data inversion technique, it is necessary to provide a pad to output flag data in addition to a pad to output actual data (e.g., Jpn. Pat. Appln. KOKAI Publication No. 2004-133961). An output pad for a read enable signal RE and a write enable signal WE is sometimes used as the flag data output pad. In this case, however, it is difficult to adjust the output timings of flag data and the signals RE and WE.